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Exercise Tied to Lower Risk for Some Types of Cancer
- jimrandomh 10y agoNo. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
- melling 10y agoJohn Oliver explains? https://www.youtube.com/watch?v=0Rnq1NpHdmw https://www.youtube.com/watch?v=0Rnq1NpHdmw
- jimrandomh 10y agoJohn Oliver pointed out that the media usually distorts what the studies say. He failed to flag the problem of junk science in high-prestige journals. (Edit: I just re-watched his segment. He does talk about P-hacking and perverse incentives, which is at least a reasonable-size chunk of the problem, just not the failure mode for this particular study.)
- arcanus 10y agoI still agree with you, he did not place enough of the blame on scientists who are unable or unwilling to properly communicate the implications of their work.
- jimrandomh 10y agoI will add that this is the sort of thing that peer review theoretically ought to stop, or at least force authors to include caveats for. Unfortunately, studies with this sort of methodology make up most of the so-called studies published, so they can't really do that.
- epistasis 10y agoI haven't read the paper itself, but even if it didn't explicitly note these caveats, it would be assumed by any reader in its intended audience. The problem is the press representation of the papers as something they're not. These types of papers should be published, because they are necessary to decide which hypotheses to test with interventional studies.
- Someone1234 10y agoThe same could be said of almost any study that tried to show this. It is unethical to design the study in the way you're suggesting (i.e. stop people exercising to see if they get cancer). They did however: > Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. So even for two thin people, exercise seems to have helped. I legitimately don't see how you could design a study that you'd be satisfied with.
- vagabondvector 10y agothe problem is that on noisy data, that adjustment of the variables isn't really as statistically clean as maths would say. it's the same with red meat causes cancer studies. they say they remove smoking and lack of exercise and still wave the statistical significance. it's very questionable how they removed the influence of these variables, since meat eaters do smoke way more, and do not exercise, and care about their health less.
- jimrandomh 10y agoActually, I think noise is a red herring, and that worrying about noise (instead of worrying about unmeasured confounders and incorrect causal structures) is how epidemiology got into this mess in the first place.
- jimrandomh 10y agoThe correct study is one where some participants get an intervention to make them exercise more, and some are left alone. There's no ethical issue, but running such a study would be difficult and expensive. Adjusting for BMI does not solve the problem, because there are many things besides BMI (unmeasured confounders) which affect both cancer risk and willingness to exercise.
- ekianjo 10y agoAnd BMI is a pseudo science measure anyway. Its been proven to be a poor indicator in about every disease many times before.
- agumonkey 10y agoI can attest to that. I had weaker health a few years ago (lack of activity mainly) but I could kick a regular schedule of activity to get back on track. An accident broke my health below the self help threshold. When you're worried you can't jog, even walk, it's hard to bootstrap the exercice-health cycle again.
- tryitnow 10y agoAn interventional study is ideal, but unlikely to happen. I would have been happy if the authors just tried to factor in other characteristics like socioeconomic status, education level, etc. It looks like they didn't do that but instead just observed an "association" which isn't terribly interesting or informative.
- aortega 10y agoI think it's pretty obvious. I believe that it is not that exercise helps, but sedentarism is poisonous. A sedentary 40 year old looks and feels 20 years older than a 40 year old athlete.
- wapapaloobop 10y agoAgreed, but it can't be as simple as merely sitting down. For example, sitting down for meditation is considered healthy, and may in fact be so.
- aortega 10y agoHealthy for the mind, sure. For you cardiovascular system? I doubt it.
- wapapaloobop 10y agohttp://archinte.jamanetwork.com/article.aspx?articleid=410453 http://archinte.jamanetwork.com/article.aspx?articleid=41045...
- fauigerzigerk 10y ago>A sedentary 40 year old looks and feels 20 years older than a 40 year old athlete. This is a completely unsubstantiated claim.
- blubb-fish 10y agoyou want a randomized study? :D
- fauigerzigerk 10y agoYes, how about taking pictures of a bunch of 40 year old marathon runners and putting it next to a picture showing a bunch of 20 year old overweight accountants and then ask people to guess the average age of each group? That should be pretty simple and covers at least the "looks" claim.
- WaBlueKey 10y agoRisks are often affected by your genetic makeup, eating and exercising habits, where you live, what type of work you do, and childhood exposure to harmful materials. There are other things that influence the risk level. Personally, staying informed and listening to my body has been my best medicine, but I'm also aware of my family history with different diseases, which helps shape my choices.
- seizethecheese 10y agoResults from the source study abstract[1]: " A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58, 95% CI 0.37-0.89), liver (HR 0.73, 95% CI 0.55-0.98), lung (HR 0.74, 95% CI 0.71-0.77), kidney (HR 0.77, 95% CI 0.70-0.85), gastric cardia (HR 0.78, 95% CI 0.64-0.95), endometrial (HR 0.79, 95% CI 0.68-0.92), myeloid leukemia (HR 0.80, 95% CI 0.70-0.92), myeloma (HR 0.83, 95% CI 0.72-0.95), colon (HR 0.84, 95% CI 0.77-0.91), head and neck (HR 0.85, 95% CI 0.78-0.93), rectal (HR 0.87, 95% CI 0.80-0.95), bladder (HR 0.87, 95% CI 0.82-0.92), and breast (HR 0.90, 95% CI 0.87-0.93). Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma (HR 1.27, 95% CI 1.16-1.40) and prostate cancer (HR 1.05, 95% CI 1.03-1.08). Associations were generally similar between overweight/obese and normal-weight individuals. Smoking status modified the association for lung cancer but not other smoking-related cancers." [1]: http://archinte.jamanetwork.com/article.aspx?articleid=2521826 http://archinte.jamanetwork.com/article.aspx?articleid=25218...
- methodover 10y agoPhew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about. If it is true that exercising regularly reduces the risk of cancer, I wonder what the mechanism is? Exercise builds muscle mass, improves lung capacity... Why would that have anything to do with cancer?
- damienkatz 10y agoI'd guess it doesn't really prevent cancer so much as boost your immune system so it can eliminate early tumors.
- trhway 10y ago>Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about. 2 out of 5 will get cancer during their lifetime. http://www.cancer.gov/about-cancer/what-is-cancer/statistics http://www.cancer.gov/about-cancer/what-is-cancer/statistics
- azdle 10y agoI don't have access to the actual paper, but my first thought on this is to wonder if they factored in the idea that people who specifically exercise are obviously interested in being healthy and may be doing other things that are "healthy" that would affect whether they get cancer or not. I wonder if it'd be possible to get data on people who are active, but not for the reason of being healthy, things like working construction, and compare that to see if it's the activity itself or just the mentality that comes from wanting to be healthy.
- mrfusion 10y agoHere's the problem with your idea though http://www.npr.org/templates/story/story.php?storyId=17792517 http://www.npr.org/templates/story/story.php?storyId=1779251... It suggests people get more benefits from exercise when they expect it. I'm curious to hear your thoughts.
- ludamad 10y agoIt's an interesting idea, but it would really need to be explored further. There's many things I see as variables that could cause the effect with the house maids, like an overly broad definition of house maids, or wrong assumptions about the type of exercise they get.
- azdle 10y agoThat's a very interesting experiment, however, at least from how it's described in that article, I don't think it's anywhere rigiorus enough to draw any conclusions from. > One possible explanation is that the process of learning about the amount of exercise they were already getting somehow changed the maids' behavior. But Langer says that her team surveyed both the women and their managers and found no indication that the maids had altered their routines in any way. She believes that the change can be explained only by the change in the women's mindset. I think that they're too quick to dismiss a change in behavior. Simply asking someone (and their managers‽) if they did anything different this month than they did last month isn't a very reliable way to figure out if there were any subtle changes in behavior. I don't know if they were expecting massive conscious changes, but I would be shocked if suddenly knowing that their daily routine is good for them didn't change some of the subconscious decisions they were making. Even just simple things like taking the stairs 10% more than they did before or how they decide when and how much to eat based on a certain level of hunger. You're still going to think "I took the stairs sometimes, but took the elevator when I needed it." or "I ate the same foods that I did before." but maybe you were taking smaller portions. Basically what I'm trying to say is that it's very hard to draw hard quantitative conclusions from vague qualitative assessments.
- birdDadCawww 10y agoNot even going to read this but cancer is pure environmental and can be avoided. some people get exposed to things and it sucks. yeah eat healthy and move spontaneously.
- ekianjo 10y ago20 percent less between super active folks and non active ones is not super convincing. If it diminished the risk by 80 percent instead it would make for a much better story
- enraged_camel 10y ago>>20 percent less between super active folks and non active ones is not super convincing. Do you mean "compelling"? Because it should definitely be convincing: it's well outside the margin of error.
- ekianjo 10y agoYeah, compelling is what I meant.
- ekianjo 10y agoThis article is poorly written. The term 'tied' is correct in the title since its an observational study, but then it jumps directly into implying a causal relationship based on the correlation. Correlation is not causation.
- known 10y agoDrink hot water and go for one hour early morning walk;
- cJ0th 10y agoIt would be interesting to see whether or not one could show that exercise is tied to higher risk for some types of cancer if they would use the same methodology analogously.